Electrical control device



April 4, 1950 M. L. ANTHONY ET AL ELECTRICAL CONTROL DEVICE mea March 19, 1948 jmm 05% WW wf @MJW Patented Apr. 4, 1950 UNITED STATES PATENT OFFICE ELECTRICAL CONTROL DEVICE Application March 19, 1948, Serial No. 15,865

' 11 Claims.

This invention relates to electrical control de vices for varying an electrical characteristic and is a. continuation in part of our copending application Ser. No. 723,819, filed January 23, 1947.

The principal, object of this invention is to provide an improved electrical control device for varying an electrical characteristic, such as capacity, and including a bimetallic strip, which is thermionically heated to varying degrees and which is mechanically coupled to an electrical control device, such as a variable condenser, for correspondingly regulating within desired limits the electrical characteristic.

In carrying out this object of the invention the electrical control device preferably includes an envelope and a resilient bimetallic strip in the envelope having one end rigidly mounted and the. remainder thereof free to flex and the bimetallic strip forming an anode which is thermionically heated by a cathode also in the envelope. The bimetallic strip flexes about its mounting in proportion to the thermionic heating which in turn may be regulated by a control grid in the envelope. A condenser is included in the envelope and has a stator and an armature which is operated :by the bimetallic strip through a one way connection. Preferably the armature is biased toward the stator and the one way connection is so arranged that the bimetallic strip holds the armature away from the stator but permits the armature to approach the stator as the bimetallic strip is thermionically heated. The movement of the armature is confined within predetermined limits but the bimetallic strip is free to fiex upon thermionic heating thereof. In this way the setting up of strains or stresses in the bimetallic strip is prevented and yet the operation of the variable condenser is maintained within fixed limits. Preferably all of the parts of the electrical control device are mounted on a common supporting disc in the envelope so that their relative positions may be accurately predetermined and the mass production thereof facilitated.

As pointed out in the aforementioned copending application, when the bimetallic strip is thermionically heated from the cathode the strip flexes about its mounting as a result of three forces: one, the plate current heats the bimetallic strip and due to unequal expansion therein the strip flexes; two, the surface of the bimetallic strip facing the cathode is heated by the plate current producing a flexing away from the oath ode and is believed to result from a radiometric effect caused by increased activity of the residual gas molecules immediately adjacent the heated surface and photoelectronic activity at the heated surface; and, three, the surface of the strip adjacent the cathode is subjected to. electron =bombardment producing av flexing away from the cathode.

The direction of flexing resulting from the first force, of course, depends upon, whether the high expanding or low expanding side of the bimetallic strip is facing the cathode and the speed of response depends upon the mass of the strip. The direction of flexing resulting from the second and third forces is always in a direction away from the cathode and the. speed of response is substantially instantaneous. These forces may be made to act cumulatively or oppositely to obtain desired results and may be predetermined with respect to each other by predetermining the thickness, mass, type and position of the bimetallic strip.

In the specific form of the invention disclosed herein, the bimetallic strip is so arranged that upon heating thereof it flexes towards the oathode and the thickness, mass and type of the bimetallic strip is such that the action due to the second and third forces is substantially eliminated.

The fields of application and use of such an electrical control device are widespread but it is found to be particularly adaptable for use in automatically tuning radio receiving sets.

Further objects of this invention reside in the details of construction of the electrical control device and in the cooperative relationship between the component parts thereof.

Other objects and advantages of this invention will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawing, in which Fig. 1 is a perspective view of the electrical control device of this invention;

Fig. 2 is a horizontal sectional view of the electrical control device;

Fig. 3 is a partial vertical sectional view of the electrical control device;

Fig. 4 is an exploded perspective view of the component parts of the electrical control device; and

Figs. 5 and 6 are enlarged views of parts of the electrical control device in different positions of operation.

The electrical control device is generally designated at l0 and includes an envelope H having a bottom I2 and an evacuating tip l3. Suitable base pins M are secured in the bottom l2 of the envelope and operate as electrical connectors 3 from the tube socket to the various elements within the envelope A base I5, cemented to the envelope H as at It, is provided with an aligning plug IT for maintaining the base pins l4 in the tube socket.

Located within the envelope I is a supporting disc 20 preferably formed of insulating material and this supporting disc is provided with holes 2| for receiving certain of the base pins M to be supported thereby. The supporting disc 20 is also provided with a hole 22 for receiving a rivet 23 and with a pair of holes 24 and 25 for receiving rivets 26 and 21 respectively.

The rivet 23 extends through a hole 30 in one end of a bimetallic strip 3|, a washer 32, a hole 33 in one end of an armature 34, a washer 35, the hole 22, an eye 36 of a spring 33, and a washer 38. The extended end of the rivet 23 is then crimped over at the washer 38 so that all of the aforementioned parts are held in proper spaced relation on the supporting disc 23 by the rivet 23.

The end of the spring 31 is provided with an upturned extension 40 extending through a hole 4| in the supporting disc 20 and engaging the under side of the armature 34. The end of the armature 34 is in turn provided with an upstanding leg 42 engaging the end of the bimetallic strip 3|. The armature 34 is preferably made of resilient metal and is urged upwardly by the spring 31. The bimetallic strip 3| has its high expanding side on the bottom and when the thermostatic strip 3| is relatively cool, it engages the leg 42 of the armature 34 to hold the free end of the armature 34 in engagement with the supporting disc 20 against the action of the spring 3'1. When the bimetallic strip 3| is thermionically heated, the free end thereof flexes upwardly to permit the spring 31 to move the free end of the armature 34 upwardly. Thus the armature is operated through a one way connection by the bimetallic strip to be positioned in accordance with the positioning of the bimetallic strip.

The rivet 26 extends through a hole 45 in a stator 46, a washer 41 and the hole 24 in the supporting disc 20. In like manner the rivet 21 extends through a hole 48 in the stator 46, a hole 49 in a strip of insulating material 50 such as mica, a washer and the hole 25 in the supporting disc 20. The extending ends of the rivets 26 and 21 are peened to mount the aforementioned parts in proper spaced relation on the supporting disc 20.

The stator 46 is preferably made of metal and it cooperates with the armature 34 with the mica strip 50 therebetween to form a variable condenser the capacity of which is varied by movement of the armature 34 with respect to the stator 46. The upward extent of movement of the armature 34 is limited by the mica strip 59 and stator 46; and the lower extent of movement is limited by the supporting disc 20. Thus the armature 34 is movable through predetermined fixed limits upon movement of the bimetallic strip 3|. When the bimetallic strip 3| is thermionically heated so as to flex upwardly the outer end thereof the armature 34 follows such movement until such time as it engages the mica strip 5|] whereupon further movement of the armature 34 is arrested and whereupon further movement of the bimetallic strip 3| is permitted. Thus as the bimetallic strip 3| is thermionically heated, its movement is at all times free and not constrained whereby the setting up of detrimental strains and stresses in the bimetallic strip is entirely eliminated and yet at the same time the movement of the armature 34 is limited within predetermined limits. This beneficial operation of the armature 34 and the bimetallic strip 3| is permitted by the one way connection between the two afforded by the upstanding leg 42 on the armature 34.

A bridge 55 formed of metal is suitably secured to the supporting disc 20 and operates to carry a cathode and grid assembly. In this connection a metal strip 55 is spot welded to the bridge 55, as at 51, and the strip 56 is provided with end pieces 58 formed of insulating material which are held in place on the strip by pins 59. The end pieces 58 support a cathode 6|) suitably heated by a filament contained therein and also support pins 6| carrying the Wires of a grid 62. The bridge 55 supports the grid and cathode assembly over the bimetallic strip 3| which operates as an anode. A plate circuit is therefore formed between the cathode 60 and the bimetallic anode strip 3| and this plate circuit is regulated by the grid 62. In other words, the cathode 60 causes thermionic heating of the bimetallic strip 3| and the amount of such thermionic heating is regulated by the grid 52. Suitable lead wires extend from the filament, cathode, grid, bimetallic element and the armature and stator of the variable condenser to the various base pins |4 so that the component parts of the control device may be electrically connected to external circuits.

The bridge 55 may also carry a getter by means of a rod 66 to aid in the evacuation of the envelope When the grid voltage is substantially negative so that there is substantially no thermionic heat-. ing of the bimetallic strip 3|, the variable condenser assumes the position shown in Fig. 5 with the armature 34 engaging the supporting disc 20 and spaced from the mica strip 5|] and the stator 46. As the grid voltage becomes less negative, the thermionic heating of the bimetallic strip 3| increases to cause the bimetallic strip 3| to flex upwardly and in so doing the armature 34 follows the bimetallic strip until such time as it engages the mica strip 50 whereupon its motion is arrested but at the same time further flexing of the bimetallic strip 3| is permitted. Thus the bimetallic strip 3|, in response to varying degrees of thermionic heating, operates to adjustably position the armature 34 within the prescribed limits.

Because the bimetallic strip included in the control device provides a slight time interval or lag in the response, the control device is admirably suited for use in automatically tuning a radio receiving set without danger of fluttering in the presence of noise or shifting signals, or over-shooting the station with an oscillating seeking action. The fact that the armature 34 operates within predetermined limits also makes it impossible for the tuning control to be moved over wide limits and still hold the station; also, the limits prevent the possibility of the receiver jumping its tuning to an adjacent channel station during fades and signal changes. As far as we are aware, no previously known automatic frequency control system has had this feature.

The control device of this invention may be utilized for the same purposes as that of the aforementioned copending application and more specifically it may be utilized in the radio systems as described and claimed in our copending application Ser. No. 15,864, filed March 19, 1948.

While for purposes of illustration one form of this invention has been disclosed, other forms thereof may becomeapparent to those skilled in the art upon reference to. thisv disclosure, and, therefore, invention is to be limited only by the scope: ofthe appended claims and prior art.

We claims as our invention:

1. An electrical control device comprising an envelope, a resilient bimetallic strip in the envelope having one end rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode in the envelope for thermionically heating the bimetallic strip to cause the same to flex about its mounting in proportion to the thermionic heating, a condenser in: the envelope including a stator and an armature moved by the. bimetallic strip, said stator being positioned between said strip and said armature 2. An electrical control device comprising an envelope, a resilient bimetallic strip in the envelope having one end rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode in the envelope for thermionically heating the bimetallic strip to cause the same to flex about its mounting in proportion to the thermionic heating, a condenser in the envelope including a stator and an armature biased toward the stator, and a one way connection between the bimetallic strip and the armature for moving the armature away from the stator when the bimetallic strip is unheated but providing free movement of the bimetallic strip and movement of the armature toward the stator when the bimetallic strip is heated.

3. An electrical control device comprising an envelope, a resilient bimetallic strip in the envelope having one end rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode in the envelope for thermionically heating the bimetallic strip to cause the same to flex about its mounting in proportion to the thermionic heating, a condenser in the envelope including a stator and an armature biased toward the stator, and a one way connection between the bimetallic strip and the armature for moving the armature away from the stator when the bimetallic strip is unheated but providing free movement of the bimetallic strip and movement of the armature toward the stator when the bimetallic strip is heated, and stops for limiting the extent of movement of the armature.

4. An electrical control device comprising an envelope, a supporting disc in the envelope, a stator carried by the supporting disc but spaced therefrom, an armature secured at one end to the supporting disc with the free end thereof between the supporting disc and the stator, an insulating strip interposed between the stator and armature for forming a variable condenser, a spring for biasing the armature toward the stator, a bimetallic strip overlying the stator and rigidly mounted at one end to the supporting disc with the remainder thereof free to flex, a one way connection between the free ends of the armature and bimetallic strip for moving the armature away from the stator, said bimetallic strip forming an anode, and a cathode carried by the supporting disc for thermionically heating the bimetallic strip to cause the same to flex upon heating to permit the armature to move toward the stator, the movement of the armature being limited by the stator and the supporting disc and the bimetallic strip being free to flex upon heating thereof.

5. An electrical control device comprising an envelope, a supporting disc in the envelope, a

stator carried by the supporting, disc, an armature secured to the supporting disc and movable with respect to the stator to form a variable condenser, a bimetallic strip secured to the supporting disc for moving the armature and forming an anode, and a cathode carried by the supporting disc for thermionically heating the bimetallic strip to. flex the same for moving the armature.

6. An electrical control device comprising an envelope, a resilient bimetallic strip. in the envelope having one. end rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode in the envelope for thermionically heating the bimetallic strip to cause the same to flex about its mounting in proportion to; the thermionic heating, a control grid in the envelope for regulating, the amount of thermionic heating, a condenser in the envelope including a stator and an armature moved by the bimetallic strip. and a leaf spring, urging said armature towards said strip.

7. An electrical control device comprising an envelope, a resilient bimetallic strip in the envelope having one end rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode in the envelope for thermionically heating the bimetallic strip to cause the same to flex about its mounting in proportion to the thermionic heating, a control grid in the envelope for regulating the amount of thermionic heating, a condenser in the envelope including a stator and an armature biased toward the stator, and a one way connection between the bimetallic strip and the armature for moving the armature away from the stator when the bimetallic strip is unheated but providing free movement of the bimetallic strip and movement of the armature toward the stator when the bimetallic strip is heated.

8. An electrical control device comprising an envelope, a supporting disc in the envelope, a stator carried by the supporting disc but spaced therefrom, an armature secured at one end to the supporting discs with the free end thereof between the supporting disc and the stator, an insulating strip interposed between the stator and armature for forming a variable condenser, a spring for biasing the armature toward the stator, a bimetallic strip overlying the stator and rigidly mounted at one end to the supporting disc with the remainder thereof free to flex, a one way connection between the free ends of the armature and bimetallic strip for moving the armature away from the stator, said bimetallic strip forming an anode, a cathode carried by the supporting disc for thermionically heating the bimetallic strip to cause the same to flex upon heating to permit the armature to move toward the stator, the movement of the armature being limited by the stator and the supporting disc and the bimetallic strip being free to flex upon heating thereof, and a control grid in the envelope for regulating the amount of thermionic heating.

9. An electrical control device comprising an envelope, a supporting disc in the envelope, a stator carried by the supporting disc, an armature secured to the supporting disc and movable with respect to the stator to form a variable condenser, a bimetallic strip secured to the supporting disc for moving the armature and. forming an anode, a cathode carried by the supporting disc for thermionically heating the bimetallic strip to flex the same for moving the armature,

and a control grid in the envelope for regulating the amount of thermionic heating.

10. An electrical control device comprising an envelope, a resilient bimetallic strip in the envelope having one end rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode in the envelope for thermionically heating the bimetallic strip to cause the same to flex about its mounting in proportion to the thermionic heating, a condenser in the envelope including a stator and an armature moved by the bimetallic strip, and a leaf spring mounted to urge said armature towards said strip.

11. An electrical control device comprising an envelope, a support in the envelope, a stator carried by the support, and an armature secured to the support and movable with respect to the stator toform a variable condenser, a bimetallic strip secured to the support for moving the armature and forming an anode, a cathode carried by the support for thermionically heating the bimetallic strip to flex the same for moving the armature, and a control electrode interposed between said cathode and said strip.

MYRON L. ANTHONY.

5 ROBERT M. VIRKUS.

REFERENCES CITED The following references are of record in the file of patent: 10 UNITED STATES PATENTS Number Name Date 1,755,796 Ruben Apr. 22, 1930 1,847,669 Ruben Mar. 1, 1932 15 1,884,591 Davis Oct. 25, 1932 2,093,331 Lynn Sept. 14, 1937 2,389,640 Ruben Nov. 27, 1945 FOREIGN PATENTS 20 Number Country Date 520,832 Great Britain May 6, 1940 

